The invention relates to a heat application transfer for decorating textiles with coloured patterns having a particularly high washing and cleaning fastness, wherein the design is produced by means of a digitally controlled colour printer.
The most common way of making transfers for the application on textiles is by means of silk screen printing where each individual colour is applied to a sheet of silicone paper. Some colours, such as vinyl and plastisol colours, are heat-activatable, but are then not very fast without further treatment. To improve the fastness, the colours are usually provided with a hot melt granulate layer in the form of a powder or a fine-grained granulate mixed in an extender base, which is applied to the colours and serves as a special glue layer between textile and colours, thereby considerably improving the fastness. At high temperatures, however, e.g. during tumbling processes which use temperatures up to 140xc2x0 C. in certain cases, they will get loose from the textile or a possible glue layer. Solvent-based two-component colours will be more stable against the action of temperature, but, when having been subjected to industrial washing and tumbling for an extended period of time, they will dry out and peel off from the textile.
The international patent application WO 92/07990 discloses a possible use of a colour copier with a two-component colour toner system in the making of a transfer for textiles. Such a two-component colour toner system, however, is not known in the market for colour copiers today. The present laser colour copiers use colour toners of a one-component thermoplastic resin type where no polymerization takes place. Furthermore, the system described in the above-mentioned international application depends on a colourless two-component extender base layer which is applied on top of the coloured image and, immediately when wet, is coated with a thermoplastic granulate which serves as a glue layer. This embodiment, however, can only be applied to white textiles, and the transferred image will only be sharp on very smooth textiles.
It is prior art to use colour copiers for the transfer of images to a thermoplastics-coated transfer paper from which it can be transferred by heat and pressure to white cotton textiles. The known products, however, exhibit great washing and cleaning weaknesses and thus just stand washing at about 40xc2x0 C. for a limited number of times. The reason is primarily that the colour toners are relatively unprotected against mechanical impacts, and that they remain heat-activatable already at temperatures from about 90xc2x0 C. Further, printing is only possible on white textiles, and only on textiles where the predominant part consists of cotton. If it is desired to transfer colour images of this type to dark textiles, up to several additional operations are required for the lamination and adaptation of a white cover layer below the colour toners. This process is both expensive and time-consuming, and it is moreover not possible to make configurative patterns, but only complete cover faces.
A number of data-controlled colour printers of various types are available which reproduce four-coloured raster images with a resolution of 400 dpi or more with an almost photographic appearance. It is not possible in a pure silk screen printing process to achieve a resolution of more than 100 dpi, and consequently fine details are lost in the reproduction. Accordingly, it would be a great advantage to be able to use such colour printers for the making of coloured and particularly multi-coloured configurative transfers for the textile industry. Of course, it would also be an advantage to be able to use data programs for the editing of images and designs together with scanners which transfer original images to data.
The object of the invention is to make a coloured configurative transfer for the textile industry which combines the great advantages achieved by the use of an electronic colour printer as the graphic unit with particularly great washing and cleaning fastness.
Since colour images generated from ordinary printers to a transfer substrate cannot readily be transferred to a textile in a configurative pattern, this is achieved according to the invention by using silk screen printing processes for making a protective layer and/or cover layer as well as a glue layer in accordance with the invention.
In its most simple embodiment the transfer of the invention is unique in that it comprises a carrier sheet having a non-binding surface which carries
(a) a one- or multi-coloured pattern printed on the carrier sheet using a digitally controlled colour printer;
(b) a transparent or white-pigmented elastomer layer of a polymer having a high plasticizing point printed configuratively on the pattern; and
(c) a heat-activatable thermoplastic polymeric glue layer printed configuratively on the transparent or white-pigmented elastomer layer, or a heat-activatable hot melt granulate sprinkled on the elastomer layer while this was still wet.
It has surprisingly been found according to the invention that the colour toners which are usually used in multi-colour copiers and which may e.g. be based on thermoplastic polyol resins, migrate into the surface of the applied transparent or white-pigmented elastomer layer and harden together with said layer under the action of the isocyanate hardener contained in the elastomer layer. The colour toners hereby lose their thermoplastic nature and remain adhered to the elastomer layer, so that the coloured pattern or the image, after the transfer has been applied to a textile, stands washing, also at elevated temperatures.
If it is desired to encapsulate the coloured pattern or image so that it will be additionally resistant to wear and to the action of washing and cleaning, it may be provided with an additional protective layer. In this embodiment the transfer of the invention is unique in that it comprises a carrier sheet having a non-binding surface which carries
(a) a first transparent elastomer layer of a polymer having a high plasticizing point printed configuratively on the carrier sheet;
(b) a one- or multi-coloured pattern printed on the first elastomer layer using a digitally controlled colour printer;
(c) a second transparent or white-pigmented elastomer layer of a polymer having a high plasticizing point printed configuratively on the pattern; and
(d) a heat-activatable thermoplastic polymeric glue layer printed configuratively on the transparent or white-pigmented elastomer layer, or a heat-activatable hot melt granulate sprinkled on the elastomer layer while this was still wet.
Further, if the transfer is intended to be applied to very coarse or uneven textiles, and if it is desired to maintain fine details in the coloured pattern or image, the transfer may be provided with both a white-pigmented and a transparent elastomer layer (c); in this case the very strongest encapsulation of the coloured pattern or image is achieved when first a transparent elastomer layer and then a white-pigmented elastomer layer are applied
In the latter embodiment the transfer of the invention is unique in that it comprises a carrier sheet having a non-binding surface which carries
(a) a first transparent elastomer layer of a polymer having a high plasticizing point printed configuratively on the carrier sheet;
(b) a one- or multi-coloured pattern printed on the elastomer layer using a digitally controlled colour printer;
(c) a second transparent elastomer layer of a polymer having a high plasticizing point printed configuratively on the pattern;
(d) a white-pigmented elastomer layer of a polymer having a high plasticizing point printed configuratively on the second transparent elastomer layer; and
(e) a heat-activatable thermoplastic polymeric glue layer printed configuratively on the white-pigmented elastomer layer, or a heat-activatable hot melt granulate sprinkled on the elastomer layer while this was still wet.
The carrier sheet having a non-binding surface may e.g. consist of paper or a heat-resistant plastics sheet, e.g. of polyester, coated with a thin layer of silicone or polyolefin; or it may e.g. consist of a polyolefin sheet, expediently a sheet of high density (HD) polypropylene.
The transparent elastomer layers may advantageously consist of an elastomeric polyurethane having a high plasticizing point applied in the form of a solution in an organic solvent. This is particularly advantageous in connection with the use of colour copiers of the dry electrostatic type which normally apply a thin silicone oil to the surface of the fixing rollers to prevent toner particles from sticking to the rollers. Small amounts of this silicone oil are applied to the colour toners in the printing and can be detrimental to the adhesion of the subsequent elastomer layer. But the organic solvent in the polyurethane layer dissolves the silicone film so that the polyurethane and the toners combine to form a homogeneous unit.
However, with other types of colour printers, or if other steps are taken to avoid the silicone film, it is also possible to use corresponding polyurethanes in aqueous solution.
The white elastomer layer, which may optionally be omitted if the transfer is to be used for applying a pattern to white textiles, may advantageously consist of the same type of polyurethane as above, pigmented with a white inorganic pigment and applied from an organic or aqueous solution.
The final glue layer may advantageously consist of polyurethane thermoplastics having a plasticizing point in the range 120-160xc2x0 C. containing dispersed fine particles of a hot melt of copolyamide or high density polyethylene type having a melting point of 100-140xc2x0 C. in the ratio 1:1, applied in the form of an organic or aqueous solution of the polyurethane with dispersed hot melt powder.
A special variation of the glue layer comprises laminating a thermoplastic moulded polyurethane sheet on the transparent or white elastomer layer. A 100 xcexcm thick transparent or coloured aromatic polyester film having a plasticizing point of about 160xc2x0 C., a hardness of 93xc2x0 Shore and an elasticity of 400% is particularly useful for the purpose. The silk screen printed polyurethane layers and the polyurethane sheet can be laminated together at 160xc2x0 C. under slight pressure, so that the sheet does not melt, but only adheres to the applied layer. During application of the finished transfer to a textile, which takes place at 200xc2x0 C. and 320 kPa in 12 seconds, the polyurethane sheet melts and forms a very strong glue layer between the textile and printed image.
In an advantageous embodiment of the invention, the transparent elastomer layers, the white elastomer layer and the glue layer are printed on the carrier sheet by silk screen printing processes in the same register and configuration on top of one another. Owing to possible inaccuracies in the register, however, the glue layer normally protrudes 1-2 mm beyond the configuration of the other layers in practice.
As stated, the one- or multi-coloured pattern is printed on the first elastomer layer using a digitally controlled colour printer. The invention is very flexible with respect to the selection of colour printer. A rough distinction may be made between digitally controlled colour printers which work with powder toners, liquid dyes or colour ribbons.
Accordingly, the coloured pattern in a transfer of the invention will normally be printed on the first transparent elastomer layer by means of a dry electrostatic colour toner printer, an ink jet printer with liquid dye or a thermotransfer colour printer, all of which are digitally controlled.
The invention also comprises a method of making a transfer as described above, said method being unique by, on a carrier sheet having a non-binding surface,
(a) printing a one- or multi-coloured pattern using a digitally controlled colour printer;
(b) on top of the pattern, configuratively printing a transparent or white-pigmented elastomer layer of a polymer having a high plasticizing point; and
(c) on top of the transparent or white-pigmented elastomer layer, printing a heat-activatable thermoplastic polymeric glue layer, or, while the elastomer layer is still wet, sprinkling a heat-activatable hot melt granulate on said layer.
Another embodiment of the method of the invention is unique by, on a carrier shet (1) having a non-binging surface,
(a) configuratively printing a first transparent elastomer layer (4) of a polymer having a high plasticizing point;
(b) on top of the first elastomer layer (4), printing a one- or multi-coloured pattern (5) using a digitally controlled colour printer;
(c) on top of the pattern (5), configuratively printing a second transparent (6) or white-pigmented (7) elastomer layer of a polymer having a high plasticizing point; and
(d) on top of the transparent (6) or white-pigmented (7) elastomer layer, configuratively printing a heat-activatable thermoplastic polymeric glue layer (8), or, while the elastomer layer is still wet, sprinkling a heat-activatable hot melt granulate on said layer.
Another embodiment of the method of the invention is unique by, on a carrier sheet having a non-binding surface,
(a) configuratively printing a first transparent elastomer layer of a polymer having a high plasticizing point;
(b) on top of the first elastomer layer, printing a one- or multi-coloured pattern using a digitally controlled colour printer;
(c) on top of the pattern, configuratively printing a second transparent elastomer layer of a polymer having a high plasticizing point;
(d) on top of the second elastomer layer, configuratively printing a white-pigmented elastomer layer of a polymer having a high plasticizing point; and
(e) on top of the white-pigmented elastomer layer, configuratively printing a heat-activatable thermoplastic polymeric glue layer, or, while the elastomer layer is still wet, sprinkling a heat-activatable hot melt granulate on said layer.
In accordance with the disclosure above, the transparent elastomer layers are advantageously applied in the form of an organic solution of an elastomer polyurethane having a high plasticizing point; but it may also take place in the form of an aqueous solution.
The white elastomer layer may then be applied in the form of a corresponding organic or aqueous polyurethane solution which is pigmented with a white pigment.
Furthermore, the glue layer may advantageously be applied in the form of an organic or aqueous solution of polyurethane thermoplastics having a plasticizing point in the range 120-160xc2x0 C., in which a fine hot melt powder of co-polyamide or high density polyethylene type having a melting point of 100-140xc2x0 C. is dispersed in the ratio 1:1.
In an advantageous embodiment of the method of the invention, the transparent elastomer layers, the white elastomer layer and the glue layer are printed on the carrier sheet by silk screen printing processes in the same register and configuration on top of one another. But, as mentioned before, owing to possible inaccuracies in the register, the glue layer will normally be printed in a configuration which protrudes 1-2 mm beyond the configuration of the other layers.
Furthermore, the coloured pattern is generally printed on the first transparent elastomer layer by means of a dry electrostatic colour toner printer, an ink jet printer with liquid dye or a thermotransfer colour printer, all of which are digitally controlled.
According to the invention, if the transfer is to be used for applying a pattern to white textiles, it is possible to omit the white elastomer layer and to print the glue layer directly on the second transparent elastomer layer.
According to the invention, if the transfer is to be used for applying a pattern to textiles having a very even and non-textured surface, it is also possible to omit the second transparent elastomer layer and to print the white elastomer layer directly on the one- or multi-coloured pattern.
Finally, according to the invention, it is also possible to omit the glue layer and, where application to white textiles is involved, optionally also the white elastomer layer, in which case the surface of the white elastomer layer and the second transparent elastomer layer, respectively, are modified to be heat-activatable. This is done most expediently according to the invention in that immediately after the printing of the elastomer layer, while this is still wet, a fine hot melt powder of copolyamide or high density polyethylene type having a melting point of 100-140xc2x0 C. is sprinkled on the surface.
The invention also comprises textile products on which a one- or multi-coloured pattern is attached by application from a transfer of the invention.
The method and the transfer of the invention give evident cost-saving advantages particularly in case of a low number of printed copies.